Fracturing construction has become a main technical method for the reformation of low permeable oil and gas reservoirs and for the development of unconventional oil and gas reservoirs. As one of effective measures for improving the recovery efficiency of oil and gas wells, fracturing construction is widely applied for increasing the production of oil and gas wells and the injection of water injection wells.
America has led the world in design and manufacturing of fracturing trucks. The manufactured fracturing truck products have the advantages of good performance, high degree of automation, high workload, large displacement and great variety. The fracturing trucks have two main models, i.e., 1490 kw and 1864 kw, with a maximum operating pressure of 160 MPa and a largest displacement of 2.7 m3/min. Since most of oil and gas wells in the North America are in plains, the overall loading capacity, the arrangement of the fracturing pump and the like are not restricted by the road conditions. Fracturing trucks of above 1864 kw are usually trailer-mounted.
In different regions and under different operating conditions, fracturing trucks are widely used for the development of oil and gas wells such as petroleum wells, coal-bed gas wells and shale gas wells in regions including lands, deserts and oceans. The fracturing trucks may be vehicle-mounted fracturing trucks, trailer-mounted fracturing trucks and skid-mounted fracturing trucks. However, due to the complex environment of shale gas reservoirs and the geographic conditions and road conditions of the construction regions in China, the fracturing trucks are required to be highly movable, safe and adaptable, with strict restrictions on their size and weight. High-power fracturing trucks are required to improve the fracturing efficiency and reduce the fracturing cost. A conventional fracturing truck usually comprises a chassis (skid chassis), an on-deck engine, a gearbox, a fracturing pump, a lubrication system, a hydraulic system, a control system, high- and low-pressure manifolds, etc.
The conventional high-power fracturing trucks have the following problems during their operation in the inland regions of China.
The power supply scheme “diesel engine-gearbox-fracturing pump” used in the fracturing trucks has the advantages of high fuel consumption, high noise pollution, high difficulty in matching the engine and the torque converter, poor operating conditions, high operating cost, etc. Furthermore, due to this scheme, the high-power diesel engine and the gearbox have large size and weight, which is disadvantageous for the miniaturized design of the vehicle-mounted scheme. It is hard to effectively solve the problems of remote wells and limited operating space in China. Furthermore, the output power of the conventional fracturing trucks driven by the diesel engine rarely exceeds 2237 kw. This is disadvantageous for the high-power development of the vehicle-mounted scheme. Particularly with higher requirements on “low-carbon green”, the effect of high-power diesel engines will be limited. The scheme of driving by the diesel engine will become the bottleneck of the development of fracturing trucks.
With the improvement to the fracturing processes and the large-scale development of unconventional oil and gas wells such as shale gas reservoirs, the fracturing construction puts forward higher requirements on the single-machine power, pressure, displacement, reliability and degree of automation of fracturing trucks. A fracturing truck having a single-machine power of below 1490 kw has already not met the “industrialized” operating requirement, i.e., over ten thousands of cubic meters of liquid and thousands of cubic meters of sand. As the core equipment for fracturing construction, the fracturing device should be designed in small volume, high power, ultrahigh pressure and large displacement.